A 68-year-old man with hypertension presents to the emergency department with sudden-onset severe back pain and hypotension (BP 90/60 mmHg). CT angiography confirms a ruptured abdominal aortic aneurysm (AAA). While awaiting surgical intervention, what is the first-line pharmacological agent to control blood pressure and reduce aortic wall stress?

## Initial Pharmacological Management of Ruptured AAA **Key Point:** In acute aortic pathology (dissection or rupture), the goal is to reduce both blood pressure AND the rate of change of pressure (dP/dt), which determines aortic wall stress. Beta-blockers are the first-line agents. ### Why Beta-Blockers First? **High-Yield:** Beta-blockers reduce myocardial contractility and heart rate, thereby decreasing dP/dt (the shear stress on the aortic wall). This is MORE important than absolute BP reduction in preventing propagation and further rupture. **Clinical Pearl:** Esmolol is preferred in acute settings because it is: - Ultra-short acting (half-life ~9 minutes) - Rapidly titratable IV - Allows quick reversal if hypotension worsens - Achieves target HR 60 bpm and systolic BP 100–120 mmHg ### Sequencing in Acute AAA Rupture 1. **Beta-blocker first** (esmolol or labetalol) → target HR 60 bpm, reduce dP/dt 2. **Then add vasodilator** (nitroprusside, nicardipine) if BP remains elevated after beta-blockade 3. **Never use vasodilators alone** — they cause reflex tachycardia and increase dP/dt, worsening aortic stress ### Esmolol vs. Labetalol | Feature | Esmolol | Labetalol | |---------|---------|----------| | Onset | <1 min | 5–20 min | | Duration | 9 min | 2–4 hours | | Route | IV only | IV or oral | | Titratability | Excellent | Good | | **Use in acute AAA** | **Preferred** | Alternative if esmolol unavailable | **Mnemonic:** **BETA-FIRST** — In acute aortic emergencies, **B**eta-blockers are **E**ssential **T**o reduce **A**ortic wall stress **F**irst, **I**nhibiting **R**eflex **S**tress and **T**achycardia. [cite:Harrison 21e Ch 242]